This invention relates to new and useful improvements in portable air filtering devices for face pieces such as masks.
Masks with forced air means have heretofore been employed to furnish filtered air to a user to protect the user from outside polluted air. Such devices for example are shown in U.S. Pat. Nos. 3,112,745 and 3,467,965. Apparatuses such as shown in these patents as well as other patents have inherent disadvantages one of which is that the ventilating protective devices are complex in construction and bulky to wear. This is especially so for apparatus of this type which is worn as complete head covers or hoods. Another disadvantage of prior apparatuses is that a single portable filtering unit cannot conveniently be adapted for use with other types of face masks, thus limiting the device to a particular use. The above disadvantages also make the prior devices costly to manufacture and uneconomical to market.